Trials near Cambridge, UK using ‘white spaces’ in unused TV spectrum have reached speeds of 8Mbps over 5.6km

Technology development company TTP’s white space link has reached speeds of 8Mbps across 5.6kms from its research and development centre near Cambridge, UK, to the nearby rural village of Orwell.

The results of these rural broadband trials were presented at a meeting on 13 December of the Cambridge TV White Spaces Consortium comprising companies such as - Arqiva, BBC, BSkyB, BT, Microsoft, Neul, Nokia, Samsung and Virgin Media – along with key policy makers from the UK and the EU.

The Consortium was formed earlier this year to explore how unused TV spectrum could provide a solution to the escalating demand for wireless connectivity from UK consumers and businesses in towns, cities and rural areas, as well as supporting new machine-to-machine (M2M) applications such as smart metering. TTP is also looking at the use of white space to replace hard-stretched emergency services communication infrastructures.

TTP has already been streaming HD TV signals across its link and demonstrated a live Skype Video call with residents of Orwell at the White Spaces Consortium meeting. TTP expects to rapidly reach speeds of greater than 12Mbps over 6km using a single TV channel, compared to wired ADSL broadband that struggles to achieve 2Mbps with less than half the range.

‘We estimate that some 600,000 premises in the UK are poorly served by wired ADSL and could be efficiently connected using cheap hardware operating in unlicensed TV white space,’ said Richard Walker, head of wireless at Cambridge-based TTP. ‘Consumers will simply have to purchase a second TV aerial along with a white space router similar in size and price to existing home routers, while we would expect charges to be similar to current ADSL costs.’

White space broadband has a practical range of up to 10km, versus just 4km for typical wired ADSL connections and the cost of deployment is significantly less than fibre over long distances. While white space works much the same way as Wi-Fi, TV spectrum signals travel farther, are better at penetrating walls and require fewer access points.

‘With the Government committed to delivering rural broadband and the support from OFCOM to make white space devices and services licence exempt, it is possible that white space technology could be launched in the UK as early as 2013,’ said Walker.

‘While there are white space trials taking place around the world in countries such as the US, Finland, Sweden, South Korea, Singapore and Japan, the White Spaces Consortium Trials in Cambridge are at the forefront of this emerging technology and bring together many of the leading players in the computing, broadcast and wireless industries,’ he said.

Central to TTP’s development effort is making sure that white space devices can’t interfere with primary users such TV receivers. This is managed by real time intelligence in the devices, which know their locations and access information from a central database to tell them which frequencies and powers they must use to avoid licensed users, and when.

TTP’s tests show that the propagation performance of its white space channel delivers very good signal to noise ratio and enough signal strength such that higher order radio modulation techniques and advanced forward error correction coding could be used to deliver even greater speeds. And using additional TV channels would also multiply bandwidth provision to rural communities.

Recent software enhancements to the radio MAC enable the system to change modulation and packet structures to scale upload and download speeds, which has a very positive impact on video conferencing and cloud-based applications by optimising the flow of traffic.

‘The key technical challenges are now being solved but the big challenge for governments and society is to change the way we manage and use spectrum on a global basis to be able to harness the full potential of white space,’ said Walker.